See Flash Plugin - Keep it up to date and troubleshoot problems

Didn't work

hello, maybe it's an issue with the protected mode in the flash plugin - you could try if disabling protected mode makes a difference.

http://blogs.adobe.com/asset/2012/06/inside-flash-player-protected-mode-for-firefox.html

Need more help solving this shockwave/adobe crashing problem

Hi jennheather, when Flash crashes, Firefox records data about what was happening leading up to the event. Sometimes this data helps identify the problem. To provide the volunteers here access to your Flash crash data, please see the last section of this article to learn how to find the crash IDs you would post here in a reply: Troubleshoot Firefox crashes (closing or quitting unexpectedly).

Also, how quickly/reliably does this happen? If you can re-create the problem easily, try Firefox's Safe Mode. That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled (Flash will still work)

In the dialog, click "Start in Safe Mode" (not Reset)

Any difference?